In view of the wide variety of products that are sold for being dispensed from containers, particularly containers with round necks which define the dispensing portal, numerous constructions have evolved for container stoppers or closure means for the portals. Generally, products such as vinegar, vegetable oils, laboratory liquids, detergents, honey, condiments, spices, alcoholic beverages, and the like, impose similar requirements on the type and construction of the closure means used for containers for these products. However, wine sold in bottles represents the most demanding product for bottle closure means, due to the numerous and burdensome requirements placed upon the closure means used for wine bottles. In view of these demands, most wine bottle closures or stoppers have been produced from a natural material known as “cork”.
Although synthetic materials have been proposed for use as wine bottle stoppers or closures, many of such products have been unable to satisfy all of the stringent requirements. As a result, cork has remained the dominant material for wine closures, in spite of the numerous inherent problems that exist with cork.
Cork represents the bark of a particular variety of cork oak, quercus suber, a tree of the oak family characteristic of western Mediterranean countries, such as Portugal, Spain, Algeria, Morocco, France, Italy, and Tunisia, that has the ability to renew its bark indefinitely. Cork is a vegetable plant comprising tissue made up of dead microcells, generally 14-sided polyhedrons, slotting in one against the other, with the intercell space filled with a gaseous mixture, essentially atmospheric air but without the carbon dioxide. It is estimated that 1 cm3 of cork numbers 15 to 40 million hexagonal cells with the thickness of the cellular membranes varying between 1 and 2.5 microns.
The suberose texture is not arranged in a uniform fashion. It is crisscrossed within its thickness by pores or ducts with walls more or less lignified, forming the lenticels. These are filled with powder of a reddish-brown color, rich in tannin. The lenticels are permeable to gases and liquids and they are often invaded by molds and other microorganisms.
The unevenness, both in membrane thickness and in the height and diameter of the cell forming the suberose parenchyma, can affect some of the cork's mechanical and physical properties, namely its compressibility and elasticity. The cork oak being able to keep its physiological process active at all times, the difference in cell size and the thickness of the cellular membrane between cork produced in spring and the succeeding autumn leave discernible rings showing the extent of each year's growth.
The contents of newly formed cells disappear during growth and the subsequent process of suberization of the membranes, on completion of which all communication with the plant's living tissues ceases. The uniqueness of quercus suber is the achieved thickness of cork bark, up to several centimeters, which insulates the tree from heat and loss of moisture and protects it from damage by animals.
In order to harvest the thick cork bark for the first time, the growth cycle takes between 20 and 30 years, depending on location, weather conditions etc. yielding the so-called virgin cork. Afterwards, some 10 years are needed between each harvest of cork boards or reproduction cork in order to gain the necessary length or diameter for some corks. Due to this process, the cork used for the manufacture of bottle closures is a reproduction of cork that is formed again after several barking phases.
The properties of cork derive naturally from the structure and chemical composition of the membranes. Because 89.7% of the tissue consists of gaseous matter, the density of cork is extremely low, about 120 to 200 kg/m3, which makes the cork light and a good insulator. Density differences can be explained by the humidity differences, the age and quality of the cork bark and the cork tree and its growth differences. The cellular membranes are very flexible, rendering the cork both compressible and elastic. Elasticity enables it to rapidly recover to its original dimensions after any deformation. Its chemical composition gives the cork the property of repelling moisture. The walls of the cells are crusted with suberin, a complex mixture of fatty acids and heavy organic alcohols.
The value of cork is further increased by its low conductivity of heat, sound and vibration due to the gaseous elements sealed in tiny, impervious compartments. Cork is also remarkably resistant to wear and has a high friction coefficient, thanks to the honeycomb structure of the suberose surface. Cork does not absorb dust and consequently does not cause allergies nor pose a risk to asthma sufferers. It is fire resistant, recyclable, environmentally friendly and a renewable product.
These advantages have made natural cork the preferred bottle closure for wine storage, particularly for medium and high quality wines where tradition, the wine mystique and the bottle opening ritual with a corkscrew, are a very important, though intangible, aspect of the wine consumption. However, numerous disadvantages of natural cork also exist and derive naturally from the structure and chemical composition of the membranes.
Because cork is a natural product, it is a limited resource. Its limitations become even more obvious with the following facts: the natural growing of cork is geographically limited to the western Mediterranean countries; the world wide annual harvest of cork oak bark is 500,000 tons and can barely be increased, because of climatic and ecological reasons; and ten-year cycles are needed between each harvest of cork boards. In order to meet the rising worldwide cork demand, the pare cycles of cork have been shortened, leading to inferior qualities and constantly rising raw material prices.
The irregularities of the cork's structure due to geographic, climatic and ecological reasons cause many quality variances. This creates a complex categorization of qualities and standards. Through different types of washing processes, various chemical agents are combined in order to decontaminate the cork and to treat the appearance of the cork. High quality corks do not need washing. The cork quality is graded, based on the number of lenticels, horizontal and vertical cracks, their sizes, and other cork specific characteristics. The grading process is a subjective task based on statistically significant populations which is difficult to perform due to its natural origin, since every cork looks, feels, functions and smells different.
Wine market experts estimate that 1% to 5% of all bottled wine is spoiled by cork taint. At least six chemical compounds have been associated with cork taint in wines. Most frequently, 2,4,6-trichloranisole (TCA) is the major culprit responsible for the offensive off-odor and impact on the flavor of the wine. TCA has an extremely low threshold for odor detection. It is detectable at concentrations as low as 1 ppt or 1.0 nanogram per liter.
In most cases, cork taint does not involve the wine-making process. Typically, the tainting chemical is not found in vineyards or in parts of the winery where the wine is produced. After the wine is bottled, the defect shows itself, thus spoiling the wine. It is almost exclusively associated with corks.
Also, there is evidence that once the corks have been treated with chlorine, and are brought into interaction with mold fungus through humidity, chloranisole is created. Other types of wine spoilage are caused by oxidation, hydrogen sulfide, volatile acidity, sulfur dioxide, brettanomyces, and mercaptans.
Another problem commonly found with natural cork is leaking bottles. Typically, the lack of tightness between the cork and the neck of the bottle causes 10% to 20% of bottle leakage. However, the majority of wine leakage is caused by passage of the wine through the cork body. These problems are most often found with lower quality cork material, which is typically porous, too soft, out of round, or out of the predetermined specifications.
In view of the fact that wine spoilage is often caused by oxidation of the wine, any gas exchange between ambient conditions and the interior of the wine bottle should be avoided. However, many corks are deformed by the chops or jaws of the bottle corking equipment, which enables air exchange and oxidation to occur. Furthermore, when bottles are stored in an environment where ideal humidity is not maintained, optimum functionality of the cork is not achieved and the cork loses its efficiency as a sealing medium by drying out, becoming brittle and/or losing its mechanical properties. These problems often cause the cork to break when pulled out of the bottle or enable wine spoilage to occur. In addition, natural cork absorbs liquids, depending on its structure and quality. This also results in breakage, while the cork is pulled out of the bottle.
Further problems or deficiencies found with natural cork are the propensity of cork worms to store or lay their eggs on the cork material, enabling the larvae to dig gullies into the cork. Consequently, enlarged apertures or channels are formed in the cork, unknown to the bottler, producing unwanted contamination and increased permeability. In addition to these drawbacks, cork powder and other cork impurities are often able to fall into the wine during the corking process, causing further problems for wine bottlers and unwanted surprises for the wine consumer.
In order to avoid some of the difficulties, bottlers have developed various spray coatings, such as paraffins, silicones and polymer materials, in an attempt to ease the movement of the cork into and out of the bottle, as well as to improve the permeability of the cork and fill imperfections in the cork surface. However, no ideal cork spray coating product has been developed to protect a wine corking member from all of the inherent difficulties or drawbacks of the material.
In particular, one of the principal difficulties to which any bottle closure is subjected in the wine industry is the manner in which the closure is inserted into the bottle. Typically, the closure is placed in a jaw clamping member positioned above the bottle portal. The clamping member incorporates a plurality of separate and independent jaw members which peripherally surround the closure member and are movable relative to each other to compress the closure member to a diameter substantially less than its original diameter. Once the closure member has been fully compressed, a plunger moves the closure means from the jaws directly into the neck of the bottle, where the closure member is capable of expanding into engagement with the interior diameter of the bottle neck and portal, thereby sealing the bottle and the contents thereof.
In view of the fact that the jaw members must be independent of each other and separately movable in order to enable the closure member to be compressed to the substantially reduced diameter, each jaw member comprises a sharp edge which is brought into direct engagement with the closure member when the closure member is fully compressed. Depending upon the composition of the closure member, score lines are frequently formed on the outer surface of the closure member, which prevents a complete, leak-free seal from being created when the closure member expands into engagement with the bottle neck.
Thus, any synthetic bottle closure must be able to withstand this conventional bottling and sealing method. Furthermore, many cork sealing members also incur damage during the bottling process, resulting in leakage or tainted wine.
Another problem inherent in the wine industry is the requirement that the wine stopper must be capable of withstanding a substantial pressure build up that occurs during the storage of the wine product after it has been bottled and sealed. Due to natural expansion of the wine during hotter months, pressure builds up, imposing a burden upon the bottle stopper that must be resisted without allowing the stopper to be displaced from the bottle. As a result, the bottle stopper employed for wine products must be capable of secure, intimate, frictional engagement with the bottle neck in order to resist any such pressure build up.
A further problem inherent in the wine industry is the requirement that secure, sealed engagement of the stopper with the neck of the bottle must be achieved virtually immediately after the stopper is inserted into the neck of the bottle. During normal wine processing, the stopper is compressed, as detailed above, and inserted into the neck of the bottle to enable the stopper to expand in place and seal the bottle. However, such expansion must occur immediately upon insertion into the bottle since many processors tip the bottle onto its side or neck down after the stopper is inserted into the bottle neck, allowing the bottle to remain stored in this position for extended periods of time. If the stopper is unable to rapidly expand into secure, intimate, frictional contact and engagement with the walls of the neck of the bottle, wine leakage will occur.
A further requirement imposed upon closures or stoppers for wine bottles is the requirement that the closure be removable from the bottle using a reasonable extraction force. Although actual extraction forces extend over a wide range, the generally accepted, conventional extraction force is typically below 100 pounds.
In achieving a commercially viable stopper or closure, a careful balance must be made between secure sealing and providing a reasonable extraction force for removal of the closure from the bottle. Since the requirements for these two characteristics are in direct opposition to each other, a careful balance must be achieved so that the stopper or closure is capable of securely sealing the wine in the bottle, preventing both leakage and gas transmission, while also being removable from the bottle without requiring an excessive extraction force.
Another requirement for commercially viable wine stoppers or closures is a low oxygen permeability. Too much oxygen can cause the premature spoilage of wine. In fact, oxidation occurs over a period of time to render the beverage undrinkable. Thus, it is necessary to effectively prevent oxygen from entering the bottle in order to extend and preserve the freshness and shelf life of the product. Any commercially viable wine stopper or closure should therefore have a low oxygen transfer rate (OTR).
Therefore, it is a principal object of the present invention to provide closure means for containers which is manufacturable from synthetic materials and effectively closes and seals any desired bottle, container, package and the like.
Another object of the present invention is to provide a synthetic closure having the characteristic features described above which is manufacturable on a continuing production basis, thus providing lower manufacturing costs compared to natural or synthetic (structured) closures and satisfying industry requirements for a removable bottle stopper which is producible substantially more economically than cork closure/stoppers.
Another object of the present invention is to provide a synthetic closure having the characteristic features described above which meets or exceeds the requisite physical characteristics found in natural closures or stoppers such as cork.
Another object of the present invention is to provide a synthetic closure or stopper having the characteristic features described above which is capable of being employed in conventional bottling equipment for being inserted into a bottle container without experiencing unwanted physical damage.
Another object of the present invention is to provide a synthetic closure or stopper having the characteristic features described above that can be substituted for a cork stopper in wine bottles, providing the desirable characteristics of conventional cork stoppers while also being removable from the bottle in the conventional manner without breaking.
Another object of the present invention is to provide a synthetic closure or stopper having the characteristic features described above, which is physiologically neutral, capable of being sterilized, as well as capable of being formed to visually simulate a desired classification of natural cork.
A further object of the present invention is to provide a synthetic closure or stopper having the characteristic features described above which is substantially odorless, remains substantially odorless in position, is substantially tasteless, and only absorbs limited amounts of water.
Another object of the present invention is to provide a synthetic closure or stopper having the characteristic features described above which is substantially unaffected by diluted acids and bases as well as substantially unaffected by most oils.
Another object of the present invention is to provide a synthetic closure or stopper having the characteristic features described above which has sufficient resistance to shrinkage, aging, apsorbtion of mold or fungus, damage from insects.
Another object of the present invention is to provide a synthetic closure or stopper having the characteristic features described above which can be mass produced on a continuing basis and eliminates the spoilage of wine due to cork taint.
Another object of the present invention is to provide a synthetic closure or stopper having the characteristic features described above which is capable of being removed from the container using conventional extraction forces, which forces remain reasonably constant regardless of the period of time over which the stopper has been in the bottle.
Another object of the present invention is to provide a synthetic closure or stopper having the characteristic features described above which is capable of being easily inserted into any desired bottle container, as well as being removed from the bottle or container without requiring excessive force.
Another object of the present invention is to provide a synthetic closure/stopper having the characteristic features described above which reduces the transfer or exchange of undesirable gases through the closure. In particular, it is an object of the present invention to provide a synthetic closure/stopper having a low oxygen transfer rate (OTR).
Other and more specific objects will in part be obvious and will in part appear hereinafter.